This is for the X-plorer GH2 Guitar, not the new Wireless GH3 one.
I've been looking at the datasheet for the Accelerometer and it actually has 4 different g-Select (sensitivity) settings, and the board is laid out so any of the 4 can be taken advantage of.
At U5 there are 4 places for Resistors, R28, R29, R30 and R31. From these 4 Resistors (just jumpers really, 0ohms) you can change the sensitivity of the Accelerometer. The way it's setup now is the most sensitive it can be, R30 and R31 in place and for some Guitars it's a bit too sensitive. To decrease it's sensitivity you just change which Resistors are installed in which places.
R30 and R31 in place - 1.5g (most sensitive) - Default setting
R28 and R30 in place - 2g
R29 and R31 in place - 4g
R28 and R29 in place - 6g (least sensitive) - Ya have to REALLY man handle the thing to get SP to go off.
It would also be possible to remove the Resistors completely and install two SPDT switches to open/close the R28 and R29 spots (R30 and R31 are internally pulled low so when the switches are off they would default to being on, same as if the Resistor were in that place so no connections need to be made there at all, but the 0ohm jumper Resistors MUST be removed if this is going to be done) and you'd have access to all 4 of the sensitivity settings, which can be changed on the fly and not hurt anything, and at the max 6g setting it's pretty much disabled really since the speed/force ya have to move it to get it to activate isn't something you'd really be doing in game.